The present invention relates to a wind turbine.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Conventional wind turbines normally have as main components a tower, a support platform rotatably attached to the upper end of the tower, and a drive train arranged on the support platform. The drive train includes a rotor which is driven by wind and attached to a rotor shaft that is mounted on a bearing block. The rotor shaft is connected to a gear unit input shaft via at least one connecting element. The output shaft of the gear unit is connected to a generator rotor arranged in a generator housing. The generator is in turn connected to a frequency converter which is designed to control the generator and to feed energy produced by the generator into a power grid.
During the operation of a wind turbine, energy is drawn from the wind flow by the rotor, as a result of which the rotor is caused to rotate. The rotary movement of the rotor is transmitted via the rotor shaft to the gear unit which increases the rotational speed. The output shaft of the gear unit in turn drives the generator, which converts mechanical energy into electrical energy which is then fed into a power grid via the frequency converter.
To cool the generator and the gear unit, conventional wind turbines have a generator cooling system and a gear unit cooling system which are normally separate from one another. The generator cooling system is usually operated with air as a cooling fluid and is provided with an air-to-air heat exchanger which is designed such that during normal operation of the wind turbine it transmits thermal energy from the air present in the interior of the generator to the cooling fluid of the generator cooling system. Oil is mostly used as the cooling fluid for the gear unit cooling system, and extracts thermal energy from the gear unit during normal operation of the wind turbine. The energy absorbed is then extracted from the oil again by a recooling medium in a recooling unit of the gear unit cooling system, whereupon the oil is fed back to the gear unit. One disadvantage of wind turbines constructed in this way is that their structure is complex and expensive.
It would therefore be desirable and advantageous to provide an improved wind turbine which obviates prior art shortcomings and is of simple and inexpensive structure while yet being reliable in operation.